Three new methods of analysis of pulmonary function data have been derived from regional 133 Xe kinetic data and regional dstribution of 99m Tc-macroaggregated albumin (MAA). These methods are regional pulmonary shunt fraction (Qs/Qt), intraregional ventilation-perfusion ratio (VA/Q) maldistribution, and total Qs/Qt. Present methods using 133 Xe produce a regional VA/Q distribution by taking the ratio of average ventilation and average blood flow in each region. The intraregional VA/Q maldistribution method overcomes the resulting loss in VA/Q resolution due to this spatial alveolar averaging by computing the VA/Q ratios for two virtual alveolar compartments in each region. Regional Qs/Qt is easily computed from radioisotope data but can not be detected from visual inspection of scintiphotos. It has proven to be clinically useful in the treatment of acute respiratory insufficiency. By extending the resolution of radioactive gas measurements, these methods help minimize the spatial averaging problem and have produced results comparable to the multiple inert gas technique. The objectives of this proposal are to develop and validate these methods with computer simulation and animal experimentation and to provide a new regional characterization and classification of the effects of experimentally induced pulmonary embolism and hemorrhagic pulmonary edema in the dog and acute respiratory insufficiency in the human.